MCAT Organic Chemistry Review 2018-2019

KEY CONCEPT

Aromatic    alcohols    are called  phenols.    The possible    resonance   between the ring    and the lone

pairs   of  the oxygen  atom    in  the hydroxyl    group   make    the hydrogen    of  the alcohol more

acidic  than    other   alcohols.

PHYSICAL PROPERTIES

One of the prominent properties of alcohols is that they are capable of intermolecular hydrogen
bonding, which results in significantly higher melting and boiling points than those of analogous
hydrocarbons, as shown in Figure 5.4.

Figure 5.4. Intermolecular  Hydrogen    Bonding in  Alcohols

MCAT EXPERTISE

Hydrogen    bonding causes  increased   melting points, boiling points, and solubility  in  water.

Molecules with more than one hydroxyl group show greater degrees of hydrogen bonding. This is
evident from the boiling points shown in Figure 5.5.

Figure 5.5. Boiling Points  for Various Alcohols

Boiling point   increases   significantly   with    additional  hydroxyl    groups, which   permit  more    hydrogen

bonding.